Chicks do not need any near as much heat as "they say" they do (the start at 90 - 95 and decrease the heat 5*/week rule). If you look at how a broody hen raises her chicks, you'll become aware that the heat lamp brooding system is a very poor substitute. Mama broody can have a very large brood of chicks, and she will brood them in very cool and sometimes wet conditions. Those chicks from the age of 2 days old and beyond are tumpling along behind and around her all day long while she searches out goodies for them to eat. Rain or shine, they are out and about frolicking in the weather. I've seen pics of very young chicks playing in the snow. They duck under Mama for a quick warm up, then they are back out to explore their world again.
They need heat, because, like all newborns, their thermal regulation system is not mature. Add to that: their down is not a good insulator like a full coat of feathers would be. This makes them more susceptible to cold AND warm temps. Overheating can be even more deadly to chicks than not giving them enough heat. Both are bad, but an overheated chick can die in a matter of hours, while a chilled chick may not die for a day or more.
At 2 weeks, you should be working on weaning them anyways. They should only have a tiny little area in their brooder where they can go to warm up. The rest of the brooder should be as cool as what ever the ambient temperatures are. Yes, definitely turn off that lamp! If they act cold, rob an incandescent bulb from a lamp and use that. I would be more concerned in your situation with them being overheated. Any time you see a chick panting, it's overheated, and you have a situation on your hands that MUST be fixed immediately.
At 2 weeks, my chicks were moved out into their coop in very nasty, cold, damp weather, by 3 weeks, they had full access to their run. I use a heating pad brooder, and was able to leave one HP up in the coop loft, and move one down into the lower level run, so that if they couldn't figure out how to get up to the loft they could still warm up. By 4 weeks, I pulled their HP.
Check out heating pad brooding by clicking on the link to Blooie's article at the bottom of my signature.